The present invention relates to a method for improving the operation of a flotation cell line, particularly in the beginning of the flotation cell line, when at least part of the flotatable material is fed past the flotation cell that is located first in the flotation cell line, when seen in the flowing direction of the flotatable material.
In a flotation cell, there are treated slurry-like materials in order to remove from the rest of the material the desired ingredients that can be utilized. The main task of the flotation cell is to keep the flotatable material in suspension, to feed air into the suspension and to disperse the suspension into small air bubbles, as well as to conduct the utilizable ingredients, i.e. the concentrate, and the rest of the material, to separate locations. However, with respect to the recovered concentrate, the efficiency of the flotation cell is essentially low. Consequently, in order to achieve the desired degree of concentration for the utilizable ingredient, the flotation cells are usually coupled in series, so that the waste from the preceding flotation cell serves as the feed for the successive flotation cell. The concentrates obtained from the cells of the accordingly created flotation cell line are then combined and conducted to further treatment.
Because the flotation cell line processes a slurry-like material, which already prior to feeding into the flotation cell line is usually treated in several different process stages, the treated slurry-like material often causes fluctuation or disturbances in the flotation cell line feed. In that case the flotation cell line must be dimensioned according to the additional load required by said fluctuations and disturbances. As the size of the flotation cells grows, the effect of said additional load grows further, because when the size of the flotation cells grows, their volume grows in proportion to the third power of the dimensions. On the other hand, the area of the flotation cells only grows in proportion to the quadrature of the longitudinal dimensions. Thus there is often reached a situation where the froth area of the flotation cell restricts the productive capacity of the cell. Said phenomenon is most obvious in a cell that is located first in the flotation cell line, when seen in the flowing direction of the flotatable material.
The object of the present invention is to eliminate some of the drawbacks of the prior art and to improve the efficiency of the flotation cell line, particularly in the beginning of the flotation cell line, where the concentrate recovery obtained from the flotation cell line is most advantageous. The essential novel features of the invention are apparent from the appended claims.
According to the invention, the efficiency of the flotation cell line is improved so that the feed, i.e. the flotatable material, fed into the flotation cell line is distributed into the flotation cell line so that at least part of the flotatable material is conducted past the cell located first in the flotation cell line, when seen in the flowing direction of the flotatable material, to at least one flotation cell that is located next in succession to the cell located first in the flotation cell line, when seen in the flowing direction of the flotatable material. This procedure prevents a situation where the fluctuations and disturbances in the feed only affect the first cell in the flotation cell line. Simultaneously it prevents any drawbacks that are caused by a possible insufficiency of the froth area of the first cell in the flotation cell line.
The improving of the efficiency of the flotation cell line according to the invention, by feeding the material to be flotated in the flotation cell line to at least two flotation cells located in the flotation cell line can be carried out so that into the first cell in the flotation cell line, when seen in the flowing direction of the flotatable material, the flotatable material is fed in a flow that is essentially homogeneous in volume. Consequently any flows that surpass said desired, essentially equally large flow of the flotatable material are conducted past the cell located first in the flotation cell line when seen in the flowing direction of the flotatable material, to another cell located in the flotation cell line. Thus any possible fluctuations and disturbances in the feeding of the flotatable material, caused by the pre-flotation process stages, can advantageously be eliminated, because in the cell located first in the flotation cell line, when seen in the flowing direction of the flotatable material, there can be created conditions that are profitable for flotation. Because flotation in general is most advantageous in the cell located first in the flotation cell line, when seen in the flowing direction of the flotatable material, by following the feeding method according to the invention there are avoided any drawbacks resulting from the fluctuations and disturbances in the feed of the flotatable material, and thus the operation in the beginning of the flotation cell line is improved.
According to the invention, the feeding of the Rotatable material can also be carried out so that the flotatable material is fed in an essentially equally large flow both to the cell located first in the flotation cell line, when seen in the flowing direction of the flotatable material, and to at least one flotation cell located in succession to said first flotation cell. Thus, when feeding the flotatable material advantageously to the first and second cells in the flotation cell line, when seen in the flowing direction of the flotatable material, essentially half of the material to be fed can be fed into both flotation cells. At the same time, the flotation period obtained for the whole material is doubled. Because the flotatable material is thus distributed between several flotation cells, each flotation cell to which non-flotated material is fed, consequently serves as the first primary flotation stage for the flotatable material. Thus the quantity of the flotatable material in the flotation cells of the flotation cell line that are successive to the primary flotation stage can be decreased, because in general the efficiency of the flow is highest in the cell of the flotation cell line that is located first in the flowing direction of the flotatable material. When the quantity of the material to be flotated in the flotation cell line is thus decreased, the control of the flotation cell line according to the invention and at the same time the control of the individual flotation cells contained in the flotation cell line is improved in order to obtain an advantageous flotation yield. As the quality of the concentrate obtained from the flotation cell line can be effectively adjusted, also the capacity of the flotation cell line can advantageously be increased.
According to the invention, into the first cell of the flotation cell line, when seen in the flowing direction of the flotatable material, there is advantageously fed fotatable material in a flow of a predetermined quantity. Any amount of the flotatable material that surpasses said predetermined quantity is advantageously conducted to the cell located second in the flotation cell line, when seen in the flowing direction of the flotatable material, said second cell being coupled either in series or in parallel with the cell located first in the flotation cell line when seen in the flowing direction.
According to the invention, the flotatable material can also be fed so that into the flotation cell located second in the flowing direction of the flotatable material, there is fed flotatable material in a flow of a predetermined quantity, and the rest of the flotatable material is fed into the flotation cell located first in the flowing direction.